const fp = require('lodash/fp');

const cars = [
    {name: 'Ferrari FF', horsepower: 660, dollar_value: 700000, in_stock: true},
    {name: 'Spyker C12 Zagato', horsepower: 650, dollar_value: 648000, in_stock: false},
    {name: 'Jaguar XKR-S', horsepower: 550, dollar_value: 132000, in_stock: false},
    {name: 'Audi R8', horsepower: 525, dollar_value: 114200, in_stock: false},
    {name: 'Aston Martin One-77', horsepower: 750, dollar_value: 1850000, in_stock: true},
    {name: 'Pagani Huayra', horsepower: 700, dollar_value: 1300000, in_stock: false},
]

// 练习1
const ex1 = fp.flowRight(fp.prop('in_stock'), fp.last);
console.log(ex1(cars)); // => false

//练习2
const ex2 = fp.flowRight(fp.prop('name'), fp.first);
console.log(ex2(cars)); // => Ferrari FF

// 练习3
let _average = function(xs) {
    return fp.reduce(fp.add, 0, xs) / xs.length;
}
const averageDollerValue = fp.flowRight(_average, fp.map(fp.prop('dollar_value')));
console.log(averageDollerValue(cars)); // => 790700

// 练习4
let _underscore = fp.replace(/\W+/g, '_');
const sanitizeName = fp.map(fp.flowRight(_underscore, fp.lowerCase));
console.log(sanitizeName(['Hello World', 'Hello Javascript'])); // => ['hello_world', 'hello_javascript']

